1. Field of the Invention
This invention relates to advanced microelectronic (semiconductor) devices and methods for fabricating the same, and in particular, to microelectronic devices employing a semi-insulating layer over a substrate.
2. Background of the Technology
Silicon carbide (SiC) is a rapidly maturing semiconductor technology that has excellent thermal conductivity and high breakdown strength. Wide bandgap materials, such as SiC and gallium nitride (GaN), have recently received significant attention for high frequency applications and other applications, including high-speed, high-power applications, such as compact, efficient radar transmitters in airborne and ground-based radar systems, as well as power integrated circuits and commercial power switching applications, such as compact fluorescent and high intensity discharge ballasts and compact battery charging systems for portable electronics. However, fundamental issues associated with substrate growth, doping, device processing, and long-term device reliability may limit their ultimate practicality. For example, a lateral structure is often selected because of its potential application in power integrated circuits, lower theoretical on-resistance than conventional vertical devices, and because of preliminary indications that lateral metal-oxide-semiconductor field effect transistors (LMOSFETs) have better radio frequency (RF) performance than vertical metal-oxide-semiconductor field effect transistors (MOSFETs). (See, e.g., M. Trivedi and K. Shenai, “The Comparison of RF Performance of Vertical and Lateral DMOSFET,” IEEE Int'l Symposium on Power Semiconductor Devices and ICs, p. 245 (May 1999), which is hereby incorporated by reference).